For questions related to building of quantum computers and discussion of the hardware aspects.
Questions tagged [architecture]
107 questions
45
votes
3 answers
How does a quantum computer do basic math at the hardware level?
On reading this Reddit thread I realized that even after a couple months of learning about quantum computing I've absolutely no clue about how a quantum computer actually works.
To make the question more precise, let's say we have a superconducting…
Sanchayan Dutta
- 17,945
- 8
- 50
- 112
26
votes
3 answers
What is the argument that practical quantum computers cannot be built?
An answer to another question mentions that
There are arguments that suggests that such machines ["quantum Turing machines"] cannot even be built...
I'm not sure I fully understand the problem, so perhaps I'm not asking the right question, but…
BurnsBA
- 363
- 3
- 5
25
votes
3 answers
Why do optical quantum computers not have to be kept near absolute zero while superconducting quantum computers do?
This is a follow-up question to @heather's answer to the question : Why must quantum computers be kept near absolute zero?
What I know:
Superconducting quantum computing: It is an implementation of a quantum computer in a superconducting electronic…
Sanchayan Dutta
- 17,945
- 8
- 50
- 112
23
votes
2 answers
What is the difference between transmon and Xmon qubits?
Transmon and Xmon qubits are two types of superconducting charge qubits that seem to be often used in superconducting quantum devices.
However, I wasn't able to easily find direct comparisons between them.
The Xmon architecture seems (1304.2322) to…
glS
- 27,510
- 7
- 37
- 125
22
votes
3 answers
Is Quantum Biocomputing ahead of us?
Now that we know of bio/molecular tools that allow living organisms to deal with quantum computations e.g. the fancy proteins that allow birds to handle quantum coherence (e.g. The quantum needle of the avian magnetic compass or Double-Cone…
AG-M
- 391
- 1
- 3
21
votes
1 answer
What cryogenic systems are suitable for superconducting qubits?
Is a dilution refrigerator the only way to cool superconducting qubits down to 10 millikelvin? If not, what other methods are there, and why is dilution refrigeration the primary method?
auden
- 3,489
- 1
- 21
- 50
20
votes
2 answers
Quantum simulation of environment-assisted quantum walks in photosynthetic energy transfer
This question is related to Can the theory of quantum computation assist in the miniaturization of transistors? and Is Quantum Biocomputing ahead of us?
About 10 years ago, several papers discussed the environment-assisted quantum walks in…
agaitaarino
- 3,907
- 2
- 13
- 42
18
votes
1 answer
How are gates implemented in a continuous-variable quantum computer?
I've mostly worked with superconducting quantum computers I am not really familiar with the experimental details of photonic quantum computers that use photons to create continuous-variable cluster states such as the one that the Canadian startup…
Mark Fingerhuth
- 1,125
- 7
- 13
18
votes
2 answers
Why must quantum computers be kept near absolute zero?
Online descriptions of quantum computers often discuss how they must be kept near absolute zero $\left(0~\mathrm{K}~\text{or}~-273.15~{\left. {}^{\circ}\mathrm{C} \right.}\right)$.
Questions:
Why must quantum computers operate under such extreme…
Didix
- 815
- 10
- 21
17
votes
3 answers
Are there any estimates on how complexity of quantum engineering scales with size?
It seems to me that an extremely relevant question for the prospects of quantum computing would be how the engineering complexity of quantum systems scales with size. Meaning, it's easier to build $n$ $1$-qubit computers than one $n$-qubit computer.…
Keith Rush
- 273
- 1
- 7
17
votes
1 answer
What is the physical representation of a qubit?
In regular computers, bits may be physically represented using a wide variety of two-state devices, such as polarity of magnetization of a certain area of a ferromagnetic film or two levels of electric charge in a capacitor.
But qubits have a…
user609
16
votes
2 answers
State of the art gate speeds and decoherence times
I am interested in the state of the art gate speeds and decoherence times for the qubit types I know are being pursued by companies presently:
superconducting qubits,
ion trap qubits,
photonic qubits.
Where can I find these, and is there a place…
user1271772 No more free time
- 14,286
- 2
- 26
- 76
15
votes
3 answers
Scalability of ion trap quantum computers
My understanding is that the magnetic fields needed to hold the ions in place in ion trap quantum computers are very complex, and for that reason, currently, only 1-D computers are possible, therefore reducing the ease of communication between…
auden
- 3,489
- 1
- 21
- 50
14
votes
2 answers
How power-efficient are quantum computers?
Quantum algorithms scale faster than classical ones (at least for certain problem clases), meaning quantum computers would require a much smaller number of logical operations for inputs above a given size.
However, it is not so commonly discussed…
Alex Jone
- 633
- 7
- 8
14
votes
4 answers
How should different quantum computing devices be compared?
In the last years, there has been a spur of demonstrations of devices able to perform proof of principle, small-scale, non-fault-tolerant quantum computation (or Noisy Intermediate-Scale Quantum technologies, how they have been referred to).
With…
glS
- 27,510
- 7
- 37
- 125